The number of individuals which is eliminated from a population whose numbers change exponentially at a rate of r per unit of time and whose mortality is d per unit of time can be calculated from Ne = (dNo/r) ( ert - 1). This formula permits the use of the concept of eliminated biomass in the calculation of production of populations without restriction to their way of reproduction. The formula was applied to calculate production of adults in the harpacticoid copepod Tachidius discipes Giesbrecht, 1882, where it was shown that the production/biomass ratio P/B = 15.